CZ209694A3 - Lubricants for chain conveyor belts and their use - Google Patents

Abstract

Clear water-soluble lubricants for chain belt conveyors contain a combination of: (a) at least one or several compounds having the general formula (1), in which R<1> stands for a saturated, mono- or polyunsaturated, linear or branched-chain alkyl residue with 6 to 22 C atoms, that may if required be substituted by -OH, -NH2, -NH-, -CO-, halogen or a carboxyl residue; R<2> stands for a carboxyl residue with 2 to 7 C atoms; M stands for hydrogen, an alkali metal, ammonium, an alkyl residue with 1 to 4 C atoms or a benzyl residue; and n stands for an integer in the range from 1 to 6; (b) at least one organic carboxylic acid selected among monobasic or multibasic, saturated, monounsaturated or polyunsaturated carboxylic acids having 2 to 22 C atoms; (c) water and additives and/or adjuvants, if required.

Description

Lubricants for chain conveyor belts and their use

Technical field

The invention relates to water-soluble, clear-chain chain conveyor lubricants comprising amphoteric compounds and organic carboxylic acids, optionally water and other additives and / or auxiliaries.

The invention also relates to the use of lubricants of the above type for the lubrication of chain conveyor belts in the food industry. These are in particular the lubrication, cleaning and disinfection of automatic devices using chain conveyor belts, in particular for the filling of food products, in particular beverages into boxes, jars, bottles, containers (KEGs) of glass or plastic or into paper packages or cardboard.

BACKGROUND OF THE INVENTION

In warehouses or cellars that contain beverage containers or bottles, or when filling food products into containers, they usually use plate or chain conveyor belts that are lubricated as they pass through the lubrication unit with various water-based lubricants or are lubricated and maintained in clean condition by automatic lubrication and cleaning systems.

In the case of wading lubrication, problems arise with regard to the technical properties and the choice of the lubricant in question, since hardly soluble salts precipitate and coatings with microbiological contamination occur. These salts and coatings can make it difficult to continuously feed the food products, especially if there are deposits on the nozzles and filters. For this reason, it is necessary to switch off the device after a certain period of operation and then clean it.

The lubricants used hitherto for this purpose are lubricants based on aliphatic saturated carboxylic acids, in particular their water-soluble alkali metal salts or alkanolamines, or lubricants based on saturated aliphatic amines in the form of organic or inorganic salts.

DE-A-23 13 330 discloses a soap-based lubricant comprising aqueous mixtures of salts of saturated aliphatic carboxylic acids having 16 to 18 carbon atoms and a surfactant.

In addition to this soap-based lubricant, primary saturated aliphatic amine-based lubricants are used. DE-A-36 31 953 discloses a method for lubricating chain conveyor belts for bottles in a bottling plant for beverages, particularly in breweries, and a method for cleaning these belts with a liquid cleaning agent. The process consists in that the chain conveyor belts for the bottles are lubricated with a neutralized primary aliphatic amine-based lubricant, preferably containing 12 to 18 carbon atoms with an unsaturated content of more than 10%, the conveyor belts being cleaned with a cationic detergent, in particular quaternary ammonium compounds , such as alkyltrimethylammonium chloride, dialkyldimethylammonium chloride or alkyldimethylbenzylammonium chloride or organic acids.

The main drawbacks of aliphatic amines are that the amines react with anions in water, especially sulfates, bicarbonates, phosphates and carbonates from alkaline water types and other substances contained in water. Strong reaction with carbonic acid from water produces poorly soluble ammonium carbonates, especially in the case of beverages containing carbonic acid. There is therefore a need for substances which can facilitate dissolution. Cleaning the spray or distribution system should be performed at regular intervals, otherwise the system will become clogged and become unusable.

Continuous 24-hour operation is not possible when using primary aliphatic amine lubricants. When using an amine of this type as a lubricant, operation can be carried out with little flexibility, since it is often necessary to use pre-mixing containers. In fact, it is necessary to use two separate work processes, one of which is lubrication and the other of cleaning, thus increasing the cost of investment in equipment. Finally, the use of primary amines and lower alkanecarboxylic acids, such as acetic acid, also results in an unpleasant odor in the purification process which impairs the working environment.

Thus, the main disadvantages of the above processes are the strong dependence of the soap-based lubricant on the water quality, and the necessity of regular cleaning of the system when using primary amine lubricants. The precipitates that result from both types of process should be removed. A simple acid-base reaction is used to remove them. In the case of aliphatic acid soap products, alkaline cleaning agents containing complexing agents are used for removal, and in the case of primary aliphatic amine products organic or inorganic acids are used for cleaning.

Finally, other chain conveyor lubricants are known which do not have the above-mentioned disadvantages. For example, EP-A-0 044 458 discloses a lubricant which is practically free from aliphatic acid soaps and comprises a carboxylated nonionic surfactant and an acyl sarcosinate. The pH of these products is in the range of 7 to 11 and therefore lies in the neutral to alkaline range.

DE-A-38 31 448 discloses a water-free, soap-free lubricant to a clear solution, a process for its preparation and its use, in particular for the lubrication of conveyor belts for glass bottles or polyethylene terephthalate bottles. A lubricant having an essentially neutral pH in the range of up to 8 in aqueous solution comprises alkylbenzene sulfonates, alkoxylated alkanolphosphates and alkanecarboxylic acids and optionally dissolution aids, solvents, antifoams and disinfectants.

However, these products also have the following three disadvantages:

1. are unsuitable from a microbiological point of view since they create conditions suitable for the growth of micro-organisms,

2. have little cleaning ability; and

3. their foaming is not easy to suppress.

DE-A-39 05 548 discloses lubricants comprising at least one secondary and / or tertiary amine and / or a salt of such an amine. However, there are some problems with the use of these hygienically acceptable substances, since many of these substances irritate the skin and, in addition, produce toxic by-products and also alkalinize the environment. Furthermore, because of their low wettability, these hydrophobic compounds can only be used in optimum operation of the conveyor belt lubrication system. In the case of organic contamination or acidification, for example phosphate contamination, the compounds are neutralized.

US-A-3,574,100 discloses amphoteric compound lubricants, containing in particular N-alkyl-1-aminopropionates and N-alkyl-beta-iminodipropionates, the alkyl groups contained being aliphatic in nature.

However, the use of these compounds in lubricants produces a high value for the coefficient of friction. Moreover, the solubility in water to a clear solution is not sufficient to use these materials in central lubrication systems in the food industry, especially in the case of fixed installed automatic systems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide novel lubricants which are better suited to these requirements. In particular, they should be water-soluble chain conveyor lubricants to clear solutions, without the aforementioned disadvantages of known lubricants. Lubricants should have a suitable value for the coefficient of friction, good lubricity, low foaming, good cleaning ability and preferably good microbicidal activity.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides lubricants for water-soluble chain conveyor belts to form a clear solution containing

a) at least one compound of formula I

R ¹ - N - (CH ₂ ) _n - COOM (I) wherein

R represents a saturated or mono- or multiply-unsaturated linear or branched alkyl radical of 6 to 22 carbon atoms, optionally substituted by -OH, -NH ₂ , -NH-, -CO-, halogen or carboxyl,

R is a carboxylic acid residue of 2 to 7 carbon atoms,

M represents a hydrogen or alkali metal atom, an ammonium group, an alkyl of 1 to 4 carbon atoms or benzyl and n represents an integer of 1 to 6,

b) at least one organic carboxylic acid which can. be mono- or polyhydric, saturated or mono- or polyunsaturated and contains 2 to 22 carbon atoms, and

c) optionally water and other additives and / or excipients.

By mixing the amphoteric surfactant and the organic carboxylic acid, a chain conveyor lubricant with very good properties is obtained. Lubrication capacity is significantly improved with a coefficient of friction / U of less than or equal to 0.12 compared to the use of amphoteric compounds alone.

Ί

Adjusting the solution to a pH that corresponds to the pH of the skin is possible. The lubricant according to the invention is not dependent on the water quality. At usual concentrations, the lubricant is poorly foaming. The lubricant has particularly good properties even after the lubricant supply is switched off while the machine is coasting. The lubricant components are well biodegradable and at the same time the material has a very good cleaning ability.

With regard to the properties in use, the lubricant according to the invention has a very good coefficient of friction, low foaming, good cleaning performance and good skin tolerance. Slight foaming improves lubrication performance in problem areas, such as points where the belt rotates and the like. Good lubrication is ensured even under unfavorable conditions, such as under-belt lubrication, the lubricant has low toxicity and is also applicable to overloaded equipment, has high capillary efficiency and produces films on surfaces, is also effective in the presence of organic impurities, acids and alkalis and, even in concentrated form, is not corrosive, it retains its efficacy even under unfavorable conditions, for example when a beverage is mixed.

When used in the beverage industry, the lubricant according to the invention, in contrast to the lubricants used hitherto, is independent of water quality, can be stored at low temperatures, non-corrosive, environmentally friendly and is well tolerated in contact with the skin.

In the compound of formula (I), the following alkyl radicals may be used, for example, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl or docosyl

Corresponding mono- or polyunsaturated residues or branched isomers may also be used. Said radicals may also be substituted by hydroxy, amino, imino, carbonyl, halogen, preferably chlorine or carboxyl groups. Particular preference is given to those compounds of the formula I which contain as the radical F @ 1 a straight saturated or unsaturated alkyl radical having 8 to 18, preferably 10 to 18, carbon atoms.

Further preferred are those compounds in which the radical R is represented by the formula - (CF3 -) - COOM, in which n and M are as defined above, i.e. the nitrogen atom of the aliphatic amine is alkylated twice with identical groups.

N in formula I is an integer from 1 to 6. Thus, it is a methylene, ethylene, propylene, butylene, pentylene or hexylene group, with the integers 2 or 3 being particularly preferred. N is particularly preferred. 2). It is further preferred that M represents a hydrogen atom or an alkali metal atom, of which alkali or potassium and especially sodium are preferred.

It is understood that the lubricant according to the invention may also contain mixtures of the compounds of the formula I. Examples of such substances are sodium N-lauryliminodipropionate, sodium N-cocosalkyliminodipropionate or sodium N-oleyliminodipropinate. These compounds may be prepared as described in US-A-3,574,100. Some of these compounds are commercially available, for example under the trade name Deriphat ^R 160C (Henkel).

The choice of organic carboxylic acid or acids is not very critical as long as the water solubility of the lubricant is maintained under the conditions of use. Accordingly, in a preferred embodiment of the invention, the organic carboxylic acid is selected from acetic acid, citric acid and glycolic acid, with acetic acid being a particularly preferred acid.

Preferred chain conveyor lubricants contain 0.01 to 95% by weight of the compounds of formula I and 5 to 50% by weight of organic carboxylic acids. It is possible to keep the chain conveyor lubricant in anhydrous form. In a particularly preferred embodiment of the invention, the chain conveyor lubricant comprises 5 to 25% by weight of the compounds of the formula I and 10 to 15% by weight of organic carboxylic acids. In addition, the chain conveyor lubricant according to the invention may contain water and optionally other additives and / or auxiliaries

Secondary and / or tertiary amines and / or salts of such amines, as described in DE-A-39 05 548, can be used as lubricant additives according to the invention.

If desired, the lubricants according to the invention may also contain N-alkyl-beta-aminopropionates having an aliphatic alkyl radical as described in the above-mentioned U.S. Pat. No. 3,574,100. EP-A-0 should also be mentioned in this connection. No. 372,628, which discloses N-alkylaminocarboxylic acids of broader meaning. These compounds are also contemplated as additives to the chain belt lubricant of the invention.

The amount of these additives which can be added to the lubricant according to the invention is generally in the range of 0 to 10% by weight, preferably 1 to 5% by weight, based on the total weight of the lubricant.

In addition, the lubricants of the present invention may contain dissolution aids or co-solvents as excipients in order to ensure the solubility of the composition in water to a homogeneous, clear solution. Examples of such substances are alcohols, polyalcohols, ethers or polyethers, in particular isopropanol, butyl glycol, butyldiglycol or ethylene glycol ether. The amount of these substances depends on the betaine used in each case, in each case the skilled person can determine the correct amount by simple preliminary experiments. In general, the amount of these substances ranges from 1 to 20% by weight, based on the total weight of the lubricant.

Other excipients include anionic or nonionic surfactants, for example alkoxylated aliphatic amines, aliphatic alcohols, alkoxylated aliphatic alcohols, but also alkylbenzene sulfonates soluble in hydrophilic solvents. These wetting agents can improve the wetting of the chain or plate conveyor belts if desired. Usually, the substances are used in an amount of 1 to 10% by weight, based on the total weight of the lubricant. Ξ nonionic surfactants are preferably used, such as aliphatic alcohol addition products with ethylene oxide and propylene oxide, especially aliphatic alcohol addition products containing 12 to 14 carbon atoms and 5E0 / 4PO.

Other adjuvants for use in the lubricant of the invention include biocidal active ingredients. In particular, quaternary ammonium compounds (QAV) containing at least one longer alkyl radical, preferably of 8 to 16 carbon atoms and / or at least one benzyl radical, optionally substituted by halogen atoms, may be used. An example is cocosalkyldimethylbenzylammonium chloride (DODIGEN ^R 225, Bayer AG). In this context, preferred biocidal active substances are also those of the alkylaminoethylene glycine type having an alkyl radical of 5 to 22, preferably 10 to 16 carbon atoms, preferably those containing two aminoethylene groups. These compounds are also referred to as TEGO ampholytes, for example, the products of Goldschmidt AG. These include, for example, [N-dodecybis (aminoethylene)] - N'-glycyin (TEGO ^R 51B, Goldschmidt AG). These biocidal active substances are generally used in an amount of 0 to 10, preferably 1 to 5% by weight, based on the total weight of the lubricant.

If desired, an anti-foaming agent can also be added to the lubricant according to the invention. These include, for example, ethylene oxide and propylene oxide addition products with aliphatic alcohols, in particular the condensation product of aliphatic alcohol and polyethylene glycol ether.

The lubricants of the invention preferably have a pH in the range of 3 to 6. If the pH of the chain conveyor lubricant is not in this range, this value can be adjusted by adding an acid, preferably an organic carboxylic acid such as those mentioned above. for example acetic acid.

For optimal dosing, it is further preferred that the lubricant have a dynamic viscosity of less than 300 mPa · s, particularly less than 150 mPa · s, a preferred range is 5 to 100 mPa · s at 20 ° C. Adjustment of the viscosity to this value is usually not necessary, if necessary additional water may be added as a diluent or co-solvent.

If the lubricant according to the invention is not exclusively composed of the compounds of the formula I and the organic carboxylic acids, the lubricant can be prepared by simply mixing said components with water and optionally adding the aforementioned additives and / or auxiliaries.

The invention also relates to the use of the lubricant according to the invention for chain conveyor belts as lubricants in the food industry, especially for equipment in automatic operations. For this purpose, the lubricant according to the invention for chain conveyor belts can generally be further diluted with water. Aqueous solutions intended for direct use generally contain from 0.01 to 1% by weight of the compounds of the formula I, preferably from 0.01 to 0.2 and in particular from 0.02 to 0.04% by weight of the compounds. The use of organic carboxylic acids can be obtained by simply recalculating the amounts indicated in the concentrates analogously to the calculations performed for the compound of formula (I).

The lubricants according to the invention have the advantage over known soap-based lubricants that they do not cause any corrosion and can therefore also be used for belts made of polyethylene terephthalate or polycarbonate materials. In addition, the lubricants according to the invention do not contain, as auxiliary substances, any wetting agents which can lead to cracks in said materials due to excessive stresses.

The following examples illustrate the invention.

EXAMPLES OF THE INVENTION

In the following Examples, the composition of the individual lubricant concentrates will be described in Examples 1 to 9 and the various data obtained during operation using appropriately diluted aqueous solutions contained 0.4% by weight of said concentrates. In addition, the importance of individual data such as friction resistance, foaming, water solubility to clear solution and running time of the device after switching off the lubricant supply will be explained. In addition, Comparative Examples 1 to 5 are also included.

All percentages given in the composition are percentages by weight.

Attempts to measure the frictional resistance, hereinafter referred to as the friction coefficient, were carried out on a conveyor belt for Technikum bottles under the following conditions.

The frictional resistance was measured using 20 water-filled 0.5 liter beer bottles using a dynamometer as a tensile stress. The bottle speed was 1 m / s. The bottle transfer belt was lubricated with a solution of the lubricant of the invention at a concentration of 0.4% by weight, as shown in the individual examples. Spraying was performed with nozzles, 4 L / h was used per nozzle and one nozzle was used for each strip.

The friction coefficient values below are quotient of the measured tensile stress per bottle relative to the bottle weight in grams.

Furthermore, the products were measured in hard water (16 ° d) according to DIN 53 902.

The foaming was determined according to the following scale; O = no foam = individual foam bubbles, = mild, non-disturbing foaming,

- disturbing foaming, = strong unacceptable foaming, foam under belt.

The friction coefficient should be less than 0.15 with sufficient lubrication. If this value is exceeded, the lubrication capacity drops and the conveyor gets stuck.

Water solubility to the clear solution should be ensured even after a prolonged period of time to avoid deposits or deposits in the ball valve filters, nozzles and spray or distribution system, on the belt and on the transported material. For this purpose, a 0.4% by weight solution in water having a hardness of 16 ° d was stored for 72 hours and then its clarity was evaluated.

The foaming of the lubricant should be low, since excess foam not only interferes with the process, in particular it can make automatic bottle inspection and work safety difficult, but it can also cause labels to peel off or foam to enter open containers. In addition, excess foam deteriorates the friction coefficient. Low foaming, on the other hand, is advantageous, since the lubricant is better distributed over the conveyor belts.

Under the experimental conditions used to determine the friction coefficient and foaming value, the lubricant supply was closed 30 minutes after the lubricant was fed to the chain conveyor belt. From this point on, lubrication was performed only with a lubricant adhering to the chain conveyor belt. The time at which sufficient lubrication can still be maintained without substantially deteriorating the friction coefficient value was measured. The end of the experiment (run-out time without lubrication) was determined as the point at which the friction coefficient decreased by 20% compared to the initial value.

Example 1% sodium N-laurylimine dipropionate% acetic acid% water friction coefficient = 0.10, foaming = 2 solubility per clear solution: the solution is almost clear run-off time without lubrication: 20 minutes.

Example 2% sodium N-lauryliminodipropionate% acetic acid% water% C12-C14 aliphatic alcohol condensation product with 5E0 / 4P0 friction coefficient: = 0,10, foaming = 1 solubility per clear solution: solution is absolutely clear deceleration time without lubrication: 25 minutes.

Example 3% sodium N-lauryliminodipropionate% citric acid% water Friction coefficient: µ = 0.11, foaming: 2 solubility per clear solution: solution is almost clear run-off time without lubrication: 15 minutes.

Example 4% sodium N-lauryliminodipropionate% glycolic acid% water friction coefficient: µ = 0.11, foaming = 1 solubility per clear solution: solution is almost clear run-off time without lubrication: not determined.

Example 5% sodium N-lauryliminodipropionate% acetic acid friction coefficient: µ = 0.10, foaming = 1 solubility per clear solution: solution is almost clear run-off time without lubrication: 20 minutes.

Example 6% sodium N-lauryliminodipropionate 14% acetic acid% water% cocosalkyldimethylbenzylammonium chloride friction coefficient: = 0.10, foaming = 1 solubility per clear solution: the solution is an absolutely clear run-off time without lubrication: 25 minutes.

Example 7% sodium N-lauryliminodipropionate% acetic acid% water% / N-dodecyl-bis (aminoethylene) - N-glycine friction coefficient: µ = 0.10, foaming = 1 solubility to clear solution: solution is absolutely clear time without lubrication: 20 minutes.

Example 8% sodium N-cocoiminodipropionate% acetic acid% water% coco dimethyl dimethyl benzylammonium chloride Friction coefficient: µ = 0.12, foaming = 0 solubility to clear solution: the solution is an absolutely clear run-off time without lubrication: 20 minutes.

Example 9% sodium N-cocoiminodipropionate% sodium N-oleyliminodipropionate% acetic acid% water% coconut dimethylbenzylammonium chloride friction coefficient: ^ u = 0.11, foaming: = 0 solubility to clear solution: solution is absolutely clear run-off time without lubrication: 20 minutes

Comparative Example 1

Lubricant for chains containing soap% water% butyldiglycol% aliphatic acid (oleic / linoleic)% sodium ethylenediaminetetraacetic acid% monoethanolamine% potassium hydroxide friction coefficient: ^ u = 0,2, foaming 3 to 4 solubility on clear solution: up to 1% solution up to hardness

12.5 ° d clear solution, run-off time without lubrication: 5 minutes.

Comparative Example 2

Lubricant for chains based on alkylamine% N, N-dimethyl-N-laurylammonium acetate 8% lauryl propylenediammonium acetate% water Friction coefficient: u u = 0.10, foaming = 1 solubility for clear solution: solution is opaque run-off time without lubrication: approximately 7 minutes .

Comparative Example 3 (US Patent 3,574,100)% N-cocosalkylaminopropionic acid 85% water Friction coefficient: µ = 0.14, foaming = 2 solubility to clear solution: solution is opaque, no lubrication time: 10 minutes.

Comparative Example 4 (US patent 3,574,100)% N-cocosalkylaminopropionic acid 3% lauryl ether phosphoric ester% water Friction coefficient: ^ u = 0.13, foaming = 4 solubility per clear solution: solution is opaque after-run time without lubrication: 7 min .

Comparative Example 5% sodium N-lauryliminodipropionate 85% water Friction coefficient: 0.12, foaming = 2 solubility to clear solution: solution is opaque, no lubrication time: 15 minutes.

Claims (12)

1. Lubricants for chain conveyor belts, soluble in water to a clear solution, characterized in that a) at least one compound of formula I wherein t> C) R - N - (CH *) - C00M i 2 n (I) 7 6 Ι.ΙΛ '1 ε (i) with f- t f · □ R represents a saturated or mono- or multiply-unsaturated linear or branched alkyl radical of 6 to 22 carbon atoms, optionally substituted by -OH, -NH ₂ , -NH-, -CO-, halogen or carboxyl, R is a carboxylic acid residue of 2 to 7 carbon atoms, M represents a hydrogen or alkali metal atom, an ammonium group, an alkyl of 1 to 4 carbon atoms or benzyl; and n represents an integer of 1 to 6, at least one organic carboxylic acid which may be mono- or polybasic, saturated or mono- or polyunsaturated and contains 2 up to 22 carbon atoms and optionally water and other additives and / or excipients, 2. Lubricants according to claim 1, characterized in that in the compound of the formula (I) is a compound of the formula (I)? - of " " R 'is a radical of the formula - (C1-6) _n - COOM, except for M, as defined above. , Lubricants according to claim 1 or 2, characterized in that in the compound of formula I * n represents an integer of 2 or 3, preferably 2. Lubricants according to one of Claims 1 to 3, characterized in that in the compound of formula (I), R ^{1 is a} straight, saturated or unsaturated alkyl radical of From 8 to 18 carbon atoms, preferably from 10 to 18 carbon atoms. Lubricants according to Claims 1 to 4, characterized in that the carboxylic acid is selected from acetic, citric and glycolic acid, preferably acetic acid. Lubricants according to claims 1 to 5, characterized in that they contain 0.01 to 95% by weight of the compound of the formula I and 5 to 50% by weight of an organic carboxylic acid. AND Lubricants according to claims 1 to 5, characterized in that they contain 5 to 25% by weight of a compound of the formula I and 10 to 15% by weight of an organic carboxylic acid. »» Lubricants according to Claims 1 to 7, characterized in that they contain auxiliary solvents, nonionic or anionic surfactants, biocidal agents and / or antifoams as auxiliary components. Lubricants according to claim 8, characterized in that they contain quaternary ammonium compounds and / or alkylaminoethylene glycines as the biocidal agent. Lubricants according to claims 1 to 9, characterized in that they have a pH of 3 to 6. Lubricants according to claims 1 to 10, characterized in that they have a dynamic viscosity of less than 300 mPa · s, in particular 5 to 100 mPa · s at 20 ° C. Use of lubricants according to claims 1 to 11 as chain lubricants in the food industry, in particular for automatic devices using chain conveyor belts, preferably in the form of a dilute aqueous solution.